Tripod with lockable helical-spiral legs



W. S. KINNARD TRIPOD WITH LOCKABLEI HELICAL-SPIRAL LEGS March 2, 1954 3 Sheets-Sheet 1 Filed Feb. 21, 1948 4 INVENTOR. Ell/046077 5. MAM @190 March 2, 1954 w. s. KINNARD I RIPOD WITH LOCKABLE HELICAL-SPIRAL LEGS 3 Sheets-Sheet 2 Filed Feb. 21, 1948 INVENTOR.

Waccarr 5 kw/yfiea BY v March 2, 1954 w. s. KlNNARD TRIPOD WITH LOCKABLEI HELICAL-SPIRAL LEGS Filed Feb. 21, 1948 3 Sheets-Sheet 3 v INV WqLcorr 5. kw/vmeo By v 'Arrokw: Y5

Patented Mar. 2, 1954 TRIPOD WITH LOCKABgE HELICAL-SPIRAL LEG Wolcott S. Kinnard, Milwaukee, Wis. Application February 21, 1948, Serial No. 10,024

14 Claims. 1

This invention relates to a tripod with lock.- able helical-spiral legs.

My improved tripod is particularly designed as a camera tripod but is adaptable for any purpose and will sustain great load in any position of adjustment in which its legs may be locked. It is the object of the invention to provide a tripod which collapses so compactly that it may readily be carried in the pocket and which may,

nevertheless, beextended to a height of five feet or more, or any intermediate adjustment, and locked.

It is a more specific object of the invention to provide a novel and improved means for looking in any desiredadjustment an axially extended helical-spiral leg.

It is another object of the invention to provide a novel relationship between a tripod head and the several telescopically extensible legs thereof, whereby the legs fold into the same plane when collapsed, but open at different angles to provide a rigid and well braced support for the head. In this connection; it will be noted from the following disclosure of the invention that when the legs are collapsed into a common plane, the head also lies in such plane, making a very compact organization. It will also be noted that the projected axes of the open legs do not intersect at a common point, as in the usual tripod. A further specific detail included in my objectives is the provision of a novel arrangement for mounting the legs pivotally in the head without exposing any mounting pintles.

The foregoing and other objects will be more apparent from the following disclosure of the invention.

In the drawings:

Fig. 1 is a view in perspective showing a fully opened tripod madein accordance with my invention.

Fig. 2 is a view in perspective showing the same tripod as it appears when opened for table top use.

Fig. 3 is a plan view showing the pattern of the metal sheets from which the individual legs of such a tripod are cut.

Fig. 4 is a detail view in cross section taken on the line 44 of Fig. 3.

Fig.5 is a plan view of a tripod embodying the invention, portions of the head being broken away to expose the interior construction.

" awayto a: sectionindicated on the line 6-6 of 2 Fig. 5, the legs so broken away being partially extended.

Fig. 7 is a. View taken in section on the line 1-1 of Fig. 8.

Fig. 8 is a fragmentary enlarged detail view in axial section through a portion of the foot and locking device of one of the tripod legs in the section indicated at 8-8 in Fig. 7.

Fig. 9 is a View taken on the section indicated by line 99 of Fig. '7 and shows the parts suggested to locking position.

Fig. 10 is a transverse sectional view taken on the line Iii-4i) of Fig. 9.

Fig. 11 is a view in perspective showing slightly separated a leg socket, a helical-spiral leg member slightly extended at its smaller end, and

the locking cup at the leg tip broken away to expose the collet to which the expanded smaller end portion of the leg is attachable.

Fig. 12 is a detail view in perspective showing in separated positions the component parts of the collet expander and one of the collets.

Fig. 13 is a detail view in perspective illustrating the component parts of the collet divider which is used in the expander shown in Fig. 12.

The tripod head [5 is provided at It, ll and I8 with downwardly opening recesses, preferably of rectangular section, to receive the correspondingly formed bearing portions I9, 20 and 2| respectively of the socket members 22, 23 and 24 of the several legs. The opposed parallel faces of the said bearing portions are closely fitted within the corresponding surfaces of the recesses in the head, whereby the socket members are guided for pivotal movement upon the axes provided.

In order that my improved tripod may be neatly and smoothly finished with no rough edges, it is desired to conceal the pintles upon which the legs are pivoted. To this end, I provide blind sockets for the pintles. It will be observed from Fig. 5 that the tripod head 15 is laterally elongated with rounded ends. The central leg socket 23 has its bearing portion 2a pivoted upon an axis which corresponds to the longitudinal axis of the head. A hole drilled into the head longitudinally at 25 from one end thereof, partially intersects the recess [8 as shown in Fig. 5. The portions of this bore immediately adjacent the recess I? receive .pintle buttons which project laterally from the bearing portion 20 of socket 23. These buttons are alike on all three of the legs and are shown in detail as applied to the bearing portion 2| of socket 24 in Fig. 5.

Between opposite buttons 26 is a compression spring 21 which projects the buttons from the apertures in the bearing portion of the socket member. Each button has a head or flange at 28 engageable with the interior surface of the socket member to limit the outward movement of the button under compression of spring 27. By compressing the spring 21, thebuttons 26, may be broughtsjuificieritlylclose together to be removed from the bearing portion 21 of the leg socket or to be introduced into the lateral apertures with which the leg socket is provided When expanded into such lateral apertures, the buttons project from the bearing portion to provide diametrically opposite pintle studs. v g r, M

The bore 29 for the pintle studs of leg socket 22 enters the tripod head l5 obliquel yfasshown in Fig. 5, and its outer end is plugged at 3il as best shown in Fig. 6. The bore 3! for'the retr actible pintle studs of the bearing portion 2! of plasterer-raise entersbbliquely, at anio posite n e a d i .n ueseda 32 ,a s o n in J' 'Thetopofthetfiiabd head [5 is recessedat 33 to receive a cover plate 34, the removalof which e 'xpose sthe fup'per ends offthe'bearing recesses "15, i'landlfl'and the upper ends of the hollow -bearing elements iBf'ZBfandZl disposed therein. ,This renders the sp irigsiTand the relatively exj p blepivot studs "28 readily accessible when the screws flfiholding cover plate 34 are released. :Ifhe recess 33 in the tr ipod head is also formed to receive 'the head "37 "011' the camera mounting screw 3i} which projects upwardly through coverplate (the knurled'head 31 being exposed at the "sides of the tripod for manipulation.

willfhereinaftr be described, the camera legsnestinto the'socket members 22,23 and '25. 'At'this'point; it is desired to observe only that when the legs are so nested and the niembersiz,

:23 amen ar folded tothe' position ShQWIl in Figs. 1

5 andie 'thetripod is'extrenrlely compact. Fig. 6 il lustrate s theactualcon mercial device in full stale. The several sockets 22,? 23 ndflzzi n lie in the 'plahe'bf the head. [As a .result, there is no point i' at which lithe lproj ectedf 'axes of the several I leg saute extended to meet. lfet the open tripod fisjextremelyfrigid when'thel'egs are spread as showninFig. '1 Of2-. -lila'chof the legs is' madef'of' 'a spirally; wound 's'tri pQof sheet metalf which may be extended by l {drawing lit I jrforf economi s fifiatefiai an for reductifc jn in [weight itispreferred that'the strip oisto'ck of fiyvhieneacrileast/mind shall'be tapered from one end "to the other, the greater width'of the strip being at. the upper end of thelegjwhie'h hasj'thegrea'ter diameter. 7 v iiilu strip is drawn outfax'ially, it win teh djjto out. axially to hel'ic el-spiral form.

in width When' such'j'a pi lly distributefthe'axial extension between its several coilsin such away that there willbe' a greater axiai' extensionatitheend where the coilsjhave the largest diameter.

Thus the g'reate'stfwidth from which the leg is made of thestrip or blank isfused at'fthe larger end'off the strip and the strip progressively decreases in width in order to maintain an approximately comparable overlap iof the respectivecoils throughout the length of "the extended leg from its larger 'to' its 'siiialler end.

While a, variety of materials may be n; 1

,ihave found it expedient to usestainless st m "spring stockof full'sprmgtemper id-Rockwell) in order to secure the necessary tensile th preferred. AI-thickness of .004 is i i )t'-s'i"ni'i "with an 'apertu stile others; xeept t e e I e by rivets -the lower and smaller extrmityof .jihdii di al l a titi e i' nfipr ict q I h v successfully employed a blank fiv'e inches wide and twelve feet long. I out this angularly to two strips 39 and 4B which are identical,

produce each'b'eing three-ahkl one-fourth inches wide at its wider end and one and three-fourths inches wide at it s narrow end. It will be noted that each 'oiltlisestrips has a finished margin at 41 'ai'id"a rawed'geWZ with a slight burr where the shearing. action has occurred. In winding the str'ipsfItake pains to dispose the burred edge on the interior of the tripod leg thus making unnecessary any refihish in'g operatioh.

I have found the thickness ofthe anetal tohe somewhat critical. "thickness of .005 inch is e I 'ciently strong, while a thickness of I006will' add 'a half pound oi weight to the tripod. g p P Each of'the identical blanks 39 fanjd lfl will provide a separate leg. To -thefsmaller ehd"43 of the strip. I'attaehareenforcin '-"plate' 44;. The

reenforcing plate the contiguousendfdftlie strip are'preferablyformed advance tothearc which these will assume in use. (In fact jthe set in the arc 'of-the'respective"coils.) I

Fig. '11 "is greatly exaggerte'd showing the leg pulled out at its smallerendfwithoiitjfthe corresponding extension {throughout its length which it willnaturally tend ftp-assume 'inpraetice. The thicknesses "oftlie iiatetalf are also necessarily exaggeratedin the several'views. "Figs. 7 to 111 show the pai ts -at twice their actual size, but even at this enlargement some exaggeratiomof the mtalthikiissis 'necessary.

At its largerend flfifiachof the strips is"provided witha tubulanloek iiig bass stteammates by a rivet and'peripherallygr'ooyed 'at'fdfto receive the loekingfspring-dii The end coilf 'is pulled axially irom' the strip *to" enable it to be bent inwardly so that; the boss fcle'ar the socket. It then snppedinto thef appropriate socket member 22 31or 24funtilfthe'boss' registers in the' side 'of' such' frhmber (see Figs. Bai'id'll). When'such registi' ation occurs, the locking boss will spring outwel dly throughfthe aperturejffnd tlie detent'jspringlil is engaged therewith toina'intahrthe' assembly,

A major feature of the present inventioneonsists in the locking means at the'lowerend breach leg whereby"'all "of" instantaneous comprising the leg ma be nicnonauy engaged with"'each other throughout the length of the leg to withstand'a lo'ad'i'ar greater thanany"which will be the oollet 'g'uicle' 55 ar"-disposed a like number-bf segmental collets'fia'having beveled upper ends at 59. To one of these aiffiafll'whiol'i'is 'identical with aperti1reli;-' r-jconnebt the spirally wound strip constituting the leg, the reenforcing plate 44 intervening. All of the collets, and also the sides of the collet guide 55, are notched to receive a contractile spiral retaining spring 6|, the sole purpose of which is to hold the collets assembled to the guide, and assure uniformity of collet movement.

The upper end of the guide carries a cone 62 bearing against the beveled faces 59 of the respective collets. The cone and the guide are integrally joined by solder or otherwise to function as one piece.

Similarly joined to the lower end of the guide is the head 64 of screw 65, the head being provided with a cruciform slot to receive the ends of the intersecting plates 56 and 51, constituting the guide. ,In this slot, the said ends are integrally secured, as by solder, so that the screw and the guide and the conical cap 62 all constitute one unitary part.

Threaded upon the screw 65 by a high pitch multiple thread is a nut 66 having a socket 61 in which is reciprocable the stop washer 68 anchored by screw 69, which is threaded into the end of screw 65. The tripod point 10 is a pressed fit over the end of nut 66 to enclose the stop washer 68 and it may be further enclosed, if desired, by a rubber foot H, the elasticity of which enables it to be snapped over the pointed foot 10 as shown in Fig. 8.

The handle for manipulating the nut 66 is a cup-shaped member 15 which is preferably fluted at 16. The diameter of this member preferably corresponds substantially with the diameter of the respective socket member 22, 23, 24. Its annular bottom is channeled downwardly to provide a shoulder at H and thence extends upwardly to constitute the frustum of a cone at 18. The upper end of the nut 66 is shouldered to receive the portion 18 of the operating member 15 and is upset thereover at 19 so that the operating handle 15 and nut 66 are rotatable as a unit.

In the position of the parts shown in Figs. 7 and 8, the nut 66 has been threaded downwardly on screw 65 substantially to the limit fixed by the stop washer 68. In this position of the parts, the collets 58 (omitted from Fig. 8) have been contracted by the spring 6|, such contraction being permitted by the separation of the fixed cone 62 carried by the core and the movable frustoconical surface 18 carried by the adjusting handle 15. In this position of the parts, the operator can freely collapse or extend the leg to any desired length within its capacity. Arriving at the desired length, it is only necessary for the operator to grasp the leg in one hand and rotate the handle l with the other in a direction to tighten the nut 66 upon the screw 65, thereby bringing toward each other the opposed conical surfaces provided by the conical cap 62 and the frustoconical portion 18 of the handle. This will expand the collets 58 thereby initiating an outward pressure on the innermost coil of the helical spiral-leg.

It will be observed that the only thing which keeps the inner core, including screw 65, from rotating with the handle 15 is the resistance of the ribbon constituting the leg. This resistance is not absolute and during the initial rotation of the handle for locking purposes, there will be some tendency for the innermost coil of the leg to rotate. However, such rotation occurs in a direction tending to expand the innermost coil, the pitch of the leg being in the same direction as the pitch of screw 65. Thus, any tendency of the innermost coil of the spring metal strip constituting the leg to rotate with the handle 15 merely distributes the locking pressure upwardly throughout the leg. Ultimately, the locking pressure willbe substantially uniformly distributedbetween all convolutions of the strip constituting the leg and each such convolution will be frictionally locked to the contiguous convolutions with such firmness that great loads can be imposed on the leg without occasioning the collapse thereof.

. Rotation of the locking handle 15 in a reverse direction on screw 65 will separate the opposing cones between which the collets are confined, thereby releasing the clamping pressure. Only a moment is required to lock each leg in its adjustment or to release each leg for readjustment or collapse.

The adjustment is infinite within the capacity of the device. Each legmay be adjusted to any length whatever from the contracted position shown in full scale in Fig. 6 to a total height which may amount to five feet or more, in the particular construction described.

For the purposes of the appended claims, the individual legs may be regarded as expansible and contractible struts. While the adjustable clamping means herein disclosed acts outwardly upon the innermost coil of the spring strip con-, stituting the strut, it is a matter of choice where the clamping device is located. In fact, where the material used is a spring strip, as in the device disclosed, a certain amount of .clamping action is exerted by the fact that the spring strip tends to expand and is confined by the tubular shell 24 at its larger end. This results in binding pressure which is communicated throughout the strut enabling it to withstand light loads, even without the adjustable means for clamping it at its other end.

I claim:

1. An extensible and collapsible strut in combination with means for locking the strut against relative change in length, the strut comprising a spirally wound elastic tape having its coils axially displaceable to vary the length of the strut, the locking device comprising an expander within the innermost coil, and an actuator comprising relatively movable parts for actuating said expander, one of said parts being provided with a handle comprising a foot extending axially beyond the innermost coil and the other of said parts being connected with the expander.

2. The combination set forth in claim 1 in which the expander comprises a core element having a conically tapered head and collets guided upon the core element and engaged with the head, at least one of said collets being connected with the innermost coil aforesaid.

3. The combination set forth in claim 1 in which the expander comprises a core element connected with the said other part and having a conically tapered head, the member part provided with the handle having an opposed conically tapered surface, and a set of collets guided by the core element and confined within the innermost coil and between the tapered head and the tapered surface aforesaid whereby the relative approach of said head and surface upon relative rotation of the screw and nut efiects expansion of the collets within said innermost coil, at least one of the collets being connected with the innermost-coil. I

expansiblez'andcontractable strut com- 72 pfisingatubular shell, a; spirally wound' striphaving-an axial. dimension such Alina-t the wound strip is. substantially receivable within the-shell; said strip having. a seriesoicoilstsubjectpto axial displacement i whereby. the: innermost; coilv may be withdrawn; axially toextend-.said-Lstrip ass-a; strut. from. said shell, means; for. frictions-11y. locking thecoils toeach other andcahandle .for' locking. and releasing; said. means, said handle prising. a cup in whichithez.smallest;coil ot said. .stripis disposed, said; cuprbeing; registered with the end of the shell when the strip. -is;-.col-, lapsed;, to constitutea. closurerforsthe end .otthe Shel-1..

An; expansible; anmcontractable. strut comprising a1 spirally: coi1ed strip; thQgSllCCdSSl-VQCOHS being. axially extensible; and: contractable;2 a cruciform core within. the; smallest coiLofirsaid strip having collet-receiving angles, colletsa disc posed in said-angles, a:conical...expandingchead connected Withthe core, a; screw-connectedwith the head, a not provided with a.handle,-.the. nut and, handle having. a-tapered camsurface. op.- positethat of said head-,5 the nutbeing. threaded to the screw for effectingsthe advanceand-ree traction ,of the head and said-surface: relative. to each; other for expanding the; collets; the innen most coil of-said strip being. connected with one of thecollets.

6; In a tripod; the combinationwith: a; head having recesses in itsunder surface,-.oneofsaid recesses opening. laterally. and; the other two opening obliquely towardthe oppositeside of the head, and axiallyextensible legs comprising-toe bular shells having extensions disposed iii-their respective:recesseaandt-provided with means piv-. oting them-individually to said-head; the said shells. normally: lying; in a. common. plane: and. being-pivotally movable in saidrecesses from said plane, said head being. provided with sockets opening into the respective recesses and said ex.- tensions being apertured and provided: with axially; movable studs proj ecting; oppositelyirom saidiextensionsand engageablesin the. respective sockets, said studszhavinginterposed:springs.urg= ing; them outwardly;to:positions.for such en agement and havingrlimiting; flanges within theex:- tensions limitingtheirz outwar-d projeotion.

7: Imatripod; the combination with. a-zhead havingirecesses in its undersurface, one of said recessesopeninglaterally and the-other two open inga obliquely towardthe oppositesideoi. the head; andaxially; extensible legs Comprising. tubular shells havingextensions disposed-intheirwrespem. tiverecesses -.and provided. with means pivoting themindividuallyto said head, the said shells normally lying. in a. common plane. andzbeing pivotally; movablein said l'ecessesfrom saidplane; said; head being. provided with sockets opening into the-respectiverecesses and said extensions being aperturedand provided with axiallymovable; studs. projecting oppositely from said ex.- tensions and engageable inthe respectivesook'ets, saidstuds having interposedsprings urging; them: outwardly: to positions for such. .engagementzand having: limiting; flanges within theextensions limiting; their outward projection, saidchead beingprovided. with a; cover: plate in removable connectiontherewith, said coven plate: afiording access tozsaid recesses.

8;; A; .tripod 1 comprising; the combination with an:elongated head-having recessesopening down-- wartime. one :Ofvfiaid-recesses: havingparallel. sides at right angles to the elongation of said headand thecother-zrecessessharinggparallelasidessdisposed 8E obliquely to each other and to thesides. or: the recesxfirst mentioned; tubular shells having up! ward extensions. disposed in. the. recesses; and substantially fitting. between the. parallel. sides. thereof, thevsaid head: having. blind. sockets. in aligned pairs. opening through the; sides: or the: recesses opposite saidextensions,..and opposed pivot-.studs'inounted. in the vrespective;extensions and engagedzin :said sockets. whereby the respece tiveshells are pivotedto saidheadthesaid head;

being providedwithv a removable. cover. plate: adapted when removed to expose saidmecesses, thelcover plate: having a camera mounting screw rotatable therein, andv the:head.having a; recess beneathpthe platein. which the'head'of saidzscrew isconfined, the diameterv of saidhead-screw. being. such; as to expose the. periphery thereof beyondsaid-tripodhead.

9; The; combination. setv forth. in claim 8-. in further combination with extensible andiretracte able legs mounted .intherespective shells when retracted and adaptedto be extended therefrom, each. of said legscomprisinga spirally coiled spring having, its outermost coil connected-tether shell and its inner coils axially extensible from. theshell, the innermost coil'being, connected with, expander, said expander including a: handleconstituting a closure forthe shell in the retracted position of th'elegr.

1D. The combination set forth in claim:t-9' in which the, expandercomprises collet; means, a core comprising a screwandragcam connected therewith, and a nut connected with said handle and having. a complementary cam,- the respective cams acting on the collet means toexpand the.

innermost coil ofsaid spring;

11. In a tripod, the combination with a tripod head of horizontally elongated form and-provided with a first reoessopening at one-side and-second and third recesses opening obliquely at theother side, said, head providing opposing bearing surfaces at. the sides of all of. said. recesses and having. sockets in thesaid surfaces, of shells having. downwardly openingcavities-of circular section and having. anchorage portions with bearing. surfaces. fitting. and engaging, those of the several recesses,v whereby to be guided from said Walls. for movement ina. predetermined plane, and studs connected with the respective anchorage portions and, engaged in. the sockets of said \vallsior pivotal connection of said shells to said head, and axially extensible legsnormally housed in the cavities of the respective shells and'extensible therefrom for the supp rt ofsaid head, the several shells being. movable upon their pivots from a common planeextending longitudinally of said headto positions of lateral extension for the stable support oisaid head, each of saidextensible legs being provided at its lower end with aunitarily 'mounted. cup constituting, in the collapsedpositionofthe leg, a- -closure for the'shell in-which such leg is-housed."

112: Theidevice of claim- 11 in. which the respective studs are retractively mounted'in the anchcrage portions of said shells and provided with compression springs urgingthem outwardly into the sockets-oi said head.

13. Anextensible and collapsible strut comprising a spirally wound elastiostrip' anda clamp disposed'withinthe strip and expansibly engageable with contiguous coilsforlockingsuch coils against. axial displacement, said-clamp comprising :parts in screw-threaded connection-and disposed-within the-coils 'of said stripior relative movement axia-lly of th'esstruti one of said parts.

being connected with one of the coils of said strip to be restrained against rotative movement therein and the other of said parts being provided with a handle exposed at the end of the strut for manipulation, said handle further comprising a foot axially extending from said strut, and a clamping element confined between the said parts and radially displaceable into clamping engagement interiorly with the said coils upon the rotation of the part provided with a handle in a direction to advance it axially of the strut upon its threaded connection with the coilconnected part, the said parts having shoulders abutting said element, said element and the shoulder of at least one of said parts being complementarily beveled for effecting expanding movement of said element upon the approach of said parts.

14. An expansible and collapsible strut comprising a spirally wound elastic strip having coils axially extensible and collapsible, and a clamp disposed within the strut and including collet elements radially movable into clamping engagement interiorly with a plurality of coils for causing said coils frictionally to engage other coils of said strut, an expander having a shoulder with which said collet elements are engaged and having radial partitions defining said collet elements in which said collet elements are disposed, one of said collet elements having a mechanical connection with one of said coils whereby to restrain the expander and collet elements from rotation, a screw-threaded extension connected with the expander, and a handle exposed outside of said strut and having a stem in screw-threaded connection with said extension, and a shoulder connected with the handle engaged with the collet elements in opposition to the expander shoulder aforesaid, the collet elements and at least one of said shoulders having complementary beveled surfaces for forcing the collet elements radially upon the approach of said shoulders.

WOLCOTT S. KINNARD.

References Cited in the file of this patent UNITED STATES PATENTS Number Name Date 289,179 Tregurtha Nov. 27, 1883 449,028 Beilmann Mar. 24, 1891 2,019,753 Wittel Nov. 5, 1935 FOREIGN PATENTS Number Country Date 5,161 Great Britain of 1900 127,530 Austria Nov. 15,1931 718,486 France Nov. 4, 1931 737,199 France Oct. 3, 1932 

